1. Field of the Invention
The present invention generally relates to brazing techniques for heat exchangers, and more particularly to a method for promoting the quality of a brazement that joins a tube to a manifold block.
2. Description of the Prior Art
Heat exchangers for automotive applications typically have tubes interconnected between a pair of manifolds. Inlet and outlet fittings are mounted to one or both manifolds, to which supply and return pipes are connected for transporting a cooling fluid to and from the heat exchanger. Inlet/outlet manifold blocks are often used as an alternative to fittings, with one manifold block typically being brazed to each manifold. A jumper tube may be brazed to the block to provide a more reliable fluidic connection between the block to another component of the heat exchanger system.
FIG. 1 shows a manifold block 10 configured in accordance with the prior art to include a flange 12 for mounting the block 10 to a manifold (not shown), and a port hole 14 for receiving a jumper tube (not shown). In accordance with conventional practice, after appropriately preparing the block 10, tube and manifold, the flange 12 of the block 10 is mated to the manifold, the tube is placed in the port hole 14, and then the block 10 is brazed to the tube and manifold during a braze cycle performed in a furnace. While adequate brazements can be achieved with manifold blocks of the type shown in FIG. 1, improved brazeability characterized by more uniform brazements between the block 10, tube and manifold would be desirable.